Orientation and microstructure topology-governed crack propagation behavior in AA7021 aluminum alloys during uniaxial tension

Abstract

The effect of textures and microstructure topologies on mechanical property evolution and tensile crack propagation behavior during uniaxial tension was systematically investigated. Results show that β-fiber textures are formed in AA7021 alloy for regular rolling and alternate rolling, respectively. While under transverse rolling the sample is mainly occupied by Copper texture components. In addition, on a macro scale, Copper texture components with low Schmid factor (hard orientation) are responsible for the higher yield strength compared to other texture components, and the significant elongation for the alternate rolling plates is attributable to the least square error of the grain size. On a micro scale, the way to improve crack deflections (tensile crack resistance) during uniaxial tension tests mainly involves two steps: intensifying Goss etc. high twist angle boundary components and decreasing residual compressive stress which aims to generate secondary cracks easily. Furthermore, there is no evidence that tensile crack deflections are relevant to tilt angle boundaries during uniaxial tension tests. Moreover, in the condition of transverse rolling, it is indicated that Brass grains with 8 movable slip systems can effectively facilitate intracrystalline extension for secondary cracks B and C, however, as to Copper, the secondary crack A only propagates along the boundaries because of the less 6 movable slip systems.